Gas generator with gas generant cushioning member and method of making thereof

ABSTRACT

A gas generator for an air bag, including a combustion chamber and a hermetic container accommodated in the combustion chamber. Gas generant pellets are charged in the hermetic container. The hermetic container has a wall adapted to be destroyed during combustion of the gas generant pellets. A partition foil piece covers a surface formed by the gas generant pellets charged in the hermetic container so as to conform to a profile of the surface formed by the gas generant pellets. The partition foil piece is non-reactive with the gas generant pellets and has a strength lower than that of the hermetic container. A cushioning member presses the partition foil piece toward the gas generant pellets by a resilient force of the cushioning member so as to suppress movement of the gas generant pellets charged in the hermetic container.

BACKGROUND OF THE INVENTION

1. Field of the Invention:

The present invention relates to a gas generator for an air bag and alsoto a method of fabricating the gas generator. Furthermore, the inventionrelates to a method of fabricating a hermetic container for receivinggas generant accommodated in a combustion chamber located inside a gasgenerator for an air bag.

More particularly, the invention relates to a gas generator for an airbag, a method of fabricating the same and a method of fabricating ahermetic container for receiving a gas generant, which preventpelletized gas generant from being powdered due to vibration.

2. Description of the Related Art:

It is known in the art of a gas generator for inflating an air bag inorder to protect passengers in a vehicle that gas generant is sealed ina hermetic container so as to prevent the gas generant from adeteriorating with a lapse of time due to absorbing moisture.

When the gas generant is shaped into pellets, the pelletized gasgenerants collide with each other or with the hermetic container due tovibration during the vehicle moving, so that the gas generant becomespowder. When the gas generant is powdered by the vibration or for othercauses, the whole surface of the gas generant increases in area and acombustion speed of the gas generant becomes rapid. Accordingly, thepressure inside of the gas generator increases. A housing of the gasgenerator may be destroyed in the worst case. Accordingly, it isnecessary to prevent the pelletized gas generant from becoming powderdue to the vibration for the purpose of preventing the gas generant fromdeteriorating as time lapses.

There is a method for preventing the pelletized gas generant frombecoming powder, where a cushion member having elasticity is insertedinto the hermetic container and vibration of the gas generant issuppressed by the elastic force. Whereby, the pelletized gas generant isprevented from becoming powder. Foamed silicone material and ceramicfiber are known as the above-described cushion member.

However, when the foamed silicone material is utilized, carbon andhydrogen contained in it act with each other during the gas generantburning. The carbon is oxidized by the action and then carbon monoxideis produced. The carbon monoxide is possible to contaminate a gasgenerated by burning gas generant. The hydrogen is oxidized by theaction and then H₂ O is produced. The H₂ O is possible to havedissolvable ingredient of the combustion residues flow out. Thecontamination of the generated gas and flowing out the dissolvableingredient of combustion residues are not suitable for the air bag.Hence, use of this material is inappropriate.

On the other hand, the ceramic fibers do not have such faults. However,these ceramic fibers constitute unwoven fabric, and each diameter of theunwoven fabric is small. Therefore, these ceramic fibers tend to bedefaced due to friction between the gas generant and the ceramic fiberscaused by vibration. Further, these ceramic fibers tend to break and bepowdered due to collision with the gas generant. Consequently,sufficient cushioning property can not be expected. For this reason, thedeterioration of the gas generant cannot be effectively prevented astime lapses.

Furthermore, it is necessary to place the cushioning member at one sidein the container so that the gas generant may be pressed against theopposite side in the container. Accordingly, it is necessary to coverthe gas generant at this one side in the container. Therefore, theamount of the cushioning member cannot be substantially reduced.

SUMMARY OF THE INVENTION

In view of the foregoing problems, the present invention has been made.It is an object of the present invention to provide a gas generatorwherein an amount of gas generant loaded in the gas generator can beincreased, and wherein a property of preventing the pelletized gasgenerant from powdering due to vibration is kept, and wherein generatedgas is not contaminated. It is another object of the present inventionto provide a method of fabricating the gas generator. It is a furtherobject of the invention to provide a method of fabricating a containerfor receiving gas generant used in the gas generator.

The problems are solved according to the present invention by providinga new gas generator for an air bag, including a combustion chamber, ahermetic container accommodated in the combustion chamber, gas generantpellets charged in the hermetic container, a partition foil piece, and acushioning member. The hermetic container has a wall adapted to bedestroyed during combustion of the gas generant pellets. The partitionfoil piece is adapted to cover a surface formed by the gas generantpellets charged in the hermetic container so as to conform to a profileof the surface formed by the gas generant pellets. The partition foilpiece is non-reactive with the gas generant pellets and has a strengthlower than that of said hermetic container. The cushioning memberpresses the partition foil piece toward the gas generant pellets by aresilient force of the cushioning member so as to suppress movement ofthe gas generant pellets charged in the hermetic container.

The hermetic container comprises a container body member for receivingthe gas generant pellets and a lid member fastened to the container bodymember.

The cushioning member is placed in the lid member. The hermeticcontainer is made of aluminum foil having a thickness of from 0.15 to0.25 mm.

In another aspect of the novel gas generator described above, sealingfoils adapted to be destroyed by a pressure of burning gas are locatedeither at exit holes for burning gas discharged from the combustionchamber or at exit openings for burning gas discharged from the gasgenerator.

Whether the gas generant pellets are placed in the combustion chamberdirectly or indirectly by means of the hermetic container, the partitionfoil piece is preferably made of aluminum foil having a thickness offrom 0.075 to 0.15 mm.

When the partition foil piece is made of a material including an ironalloy, a stainless steel foil, which has a thickness of from 0.02 to0.04 mm in order to obtain a strength lower than that of the hermeticcontainer, is suitable as the partition foil piece.

In addition, the cushioning member is preferably made of unwoven fabricconsisting of ceramic fibers.

A method of fabricating a container for receiving gas generant pelletsaccording to the present invention is one of methods concerningfabricating the hermetic container accommodated in the novel gasgenerator.

In the method, gas generant pellets are charged into a container bodymember of the gas generant container including thin walls adapted to bedestroyed during combustion of the gas generant pellets. A partitionfoil piece is placed on a surface formed by the gas generant pelletscharged in the container body member. The partition foil piece isnon-reactive with the gas generant pellets and has a strength lower thanthat of the container body member. The gas generant pellets charged inthe container body member are pressed and vibrated so as to be denselycharged in said container body member. The gas generant pellets arepressed via the partition foil piece such that the partition foil pieceis deformed so as to substantially conform to a profile of the surfaceformed by the gas generant pellets charged in the container body member.A lid member having a cushioning member therein is fastened to thecontainer body member so as to press the partition foil piece toward thegas generant pellets.

In another method of fabricating a gas generator of an air bag, gasgenerant pellets are charged into a combustion chamber located inside abody of the gas generator including sealing foils adapted to bedestroyed by a pressure of burning gas during combustion of the gasgenerant pellets. The sealing foils are placed either at exit holes forburning gas discharged from the combustion chamber or at exit openingsfor burning gas discharged from the body of the gas generator. Apartition foil piece is placed on a surface formed by the gas generantpellets charged in the combustion chamber. The partition foil piece isnon-reactive with the gas generant pellets and is deformable so as tosubstantially conform to a profile of the surface formed by the gasgenerant pellets charged in the combustion chamber. The gas generantpellets charged in the combustion chamber are pressed and vibrated so asto be densely charged in the combustion chamber. The gas generantpellets are pressed via the partition foil piece such that the partitionfoil piece is deformed so as to substantially conform to the profile ofthe surface formed by the gas generant pellets. A cushioning member isset on the partition foil piece. The body of the gas generator is closedwith a cover.

If the size of the space for accommodating the cushioning member cannotbe established accurately in the closing step, the cushioning member maybe fixed in the combustion chamber with a holding member in the settingstep. The closing step is carried out easily by pressing the coveragainst the body of the gas generator with friction between them.

The pressing steps in both methods of fabricating the container and thegas generator may be carried out with a press member having a presssurface which faces to the partition foil piece and which has a concavecurved shape and a deformable pressure-transmitting member.

The operation of the above-described configuration is now described.

In the above-described configuration, the presence of the partition foilpiece between the charged pellets of the gas generant and the cushioningmember prevents the pellets from colliding with or rubbing against thecushioning member due to vibration. Therefore, the cushioning member canmaintain its characteristics of suppressing the movement of the pelletseven though time lapses. Hence, the gas generant pellets are preventedfrom powdering due to vibration.

And, the partition foil piece is non-reactive with the gas generant.Therefore, the partition foil piece does not react with the gas generantduring combustion of the gas generant and does not contaminate generatedgas.

Moreover, when the cushioning member is made of unwoven fabricconsisting of ceramic fibers, the cushioning member also does not reactwith the gas generant during combustion of the gas generant. Hence, thegenerated gas also is not contaminated by the cushioning member. Andsafety for a passenger is assured.

Additionally, since the gas generant pellets charged in the container orthe combustion chamber are not directly pressed by the cushioningmember, the charged gas generant pellets contact with the partition foilpiece directly. Consequently, it is not necessary for the cushioningmember to press a whole surface formed by the charged gas generantpellets if the partition foil piece has an appropriate strength.Therefore, an amount of the cushioning member can be reduced, and anamount of the charged gas generant pellets can be increased.

The appropriate strength is sufficient to maintain the shape of the foilafter it is deformed substantially according to the profile of thesurface formed by the charged pellets.

When the partition foil piece is made of aluminum, the appropriatestrength is obtained by setting the thickness of the foil from 0.075 to0.15 mm. When the partition foil piece is made of stainless steelincluding an iron alloy-material, the appropriate strength is obtainedby setting the thickness of the foil from 0.02 to 0.04 mm.

When the hermetic container is composed of the container body member andthe lid member, the gas exit holes can be formed at a lower or sideportion of the combustion chamber if the cushioning member is placed inthe lid member.

In the fabrication method according to the present invention, thepartition foil piece provided with the appropriate strength keeps thedeformation conforming to the profile of the surface formed by thecharged gas generant pellets even if the pressing force used in thepressing step is removed. Therefore, the surface formed by the chargedgas generant pellets does not lift up. And a finished product has adensely charged state of the gas generant. In consequence, the containerand the gas generator according to the present invention can be chargedwith more amount of the gas generant pellets than heretofore.

When the press member has a material which is deformable andtransmittable with respect to pressure and has a concave curved surfacefacing to the partition foil piece, the surface formed with the chargedpellets of the gas generant is made convex. Therefore, the containerbody member can be hermetically closed with the lid member of thecontainer without difficulty caused by an existence of the gas generant.And also the body of the gas generator can be closed with the coverwithout difficulty caused by an existence of the gas generant.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a gas generant container that is ahermetic container used in a gas generator according to the presentinvention;

FIGS. 2(a)-2(e) are views illustrating the sequence of steps of a methodfor fabricating a gas generant container for use with the novel gasgenerator;

FIG. 3 is a cross-sectional view of a gas generator according to thepresent invention; and

FIG. 4 is a cross-sectional view of another gas generator according tothe invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Embodiments of the present invention are hereinafter described withreference with the accompanying drawings. A gas generator according tothe present invention is first described by referring to FIG. 1.

Referring to FIG. 1, there is shown a gas generant container 1 that is ahermetic container constituting a gas generator according to theinvention. This gas generant container 1 is accommodated in a combustionchamber of the gas generator for an automobile air bag.

In FIG. 1, the gas generant container 1 comprises a container bodymember 2a and a lid member 2b fitting over the container body member 2a.

The gas generant container 1 is an annular hermetic container 2 in whichan end portion (a) of the lid member 2b is crimped so as to clamp edgesof the container body member 2a. The container body member 2a of thehermetic container 2 is charged with gas generant pellets 3. An annularcushioning member 4 is placed in a recessed portion of the lid member2b. An annular partition foil piece 5 is disposed between the cushioningmember 4 and the gas generant 3 in contact with both of them. Thepartition foil piece 5 is placed so as to cover the recessed portion ofthe lid member 2b. The partition foil piece 5 has edge portions 5a,conforming to the profiles of the edges of the recessed portion of thelid member 2b.

The hermetic container 2 can be used in a gas generator having gas exitholes at a lower or side portion of a gas generating chamber providedthe lid member 2b having the cushioning member 4 in it.

It is also possible to place the cushioning member 4 at the bottom ofthe container body member 2a of the hermetic container 2. In this case,the container can be used in a gas generator having gas exit holes at anupper or a side portion of a gas generating chamber.

For example, the hermetic container 2 is made of a thin sheet ofaluminum whose thickness has a range of about from 0.15 to 0.25 mm. Thisthickness brings about a destruction of the container when the gasgenerant 3 burns. The cushioning member 4 can be made of unwoven fabricconsisting of ceramic fibers, whose thickness is 2 mm, so as to preventthe generated gas from becoming contaminated.

Preferably, the partition foil piece 5 is made of a material which doesnot act with the gas generant 3 so as to prevent the generated gas frombeing contaminated. In order to suppress the movement of the surfaceformed by the charged pellets of the gas generant during fabrication asdescribed later and to prevent the charged pellets from becoming powder,it is necessary for the partition foil piece to deform appropriatelyaccording to the profile of the surface formed by the charged pellets ofthe gas generant and to keep the deformed shape. For these reasons, thepartition foil piece preferably has appropriate deformability andstrength.

The hermetic container 2 is likely to be damaged to rub against thepartition foil piece 5 when the partition foil piece 5 is in directlycontact with the hermetic container 2 and the strength of the partitionfoil piece 5 is greater than that of the hermetic container 2.Consequently, the hermetic container 2 is possibly opened.

Therefore, the material of the partition foil piece 5 preferably has astrength lower than that of the hermetic container 2. Aluminum satisfiesthese conditions. In the present example, both components are made ofaluminum. Preferably, the thickness of the partition foil piece 5 is setfrom 0.075 to 0.15 mm. When the thickness is less than 0.075 mm, thestrength is insufficient. A vibration experiment in which accelerationsof ±5 G are applied was conducted. As the result of it, the partitionfoil piece 5 was broken when the thickness was 0.05 mm.

When the thickness of the partition foil piece 5 is greater than 0.15mm, the strength of the hermetic container 2 may be lower than that ofthe partition foil piece 5 since the minimum thickness of the hermeticcontainer 2 is 0.15 mm. The hermetic container 2 is likely to have holeson it. Therefore, in the present embodiment, the thickness of thepartition foil piece 5 is set at 0.1 mm.

When the gas generant 3 is made of azide-based agents, the gas generant3 has a property of absorbing moisture. For this reason, the gasgenerant is hermetically sealed in the hermetic container 2.

The hermetic container 2 of the present invention also can be applied toother types of gas generants which do not have the property of absorbingmoisture. Because, the hermetic container 2 is used in order to preventgas generant powder from flowing out a gas generator.

The operation and the effects are next described. In FIG. 1, theresilient force of the cushioning member 4 acts on the gas generant 3through the partition foil piece 5. Even if external vibrations areapplied, movement of the gas generant 3 is suppressed. Thus the gasgenerant pellets are prevented from being powdered.

In this case, the aluminum partition foil piece 5 is interposed betweenthe gas generant 3 and the cushioning member 4, the cushioning member 4can not be in direct contact with the gas generant. The gas generantpellets 3 do not collide with or rub against the cushioning member 4 dueto vibration.

Therefore, even if the cushioning member 4 is made of ceramic fiberswhich tend to wear out, it is possible that the gas generant pelletshave been prevented from becoming powder for lapse of long time.Furthermore, the partition foil piece 5 of aluminum does not act withthe gas generant.

In addition, it is not necessary for the cushioning member 4 to supportthe whole surface formed by the charged pellets 3 of the gas generantsince the partition foil piece 5 has the appropriate strength. Withrespect to the cushioning member 4, it is only necessary to take accountof the resilient force. So, it is possible to reduce an amount of thecushioning member 4. The amount of cushioning member was 3.3 g in theprior art while, for example, the amount of cushioning member may be 1.5g in the present invention. In this way, even if the amount ofcushioning member is reduced to half, in the present invention, themovement of the gas generant due to vibration is more suppressed thanprior art.

For this reason, even if the inside volume of the hermetic container 2was the same as that of the prior art container, the container can becharged with more amount of gas generant comparing to the conventionalcontainer.

A method of fabricating the gas generant container 1 for the novel gasgenerator in accordance with the present invention is described byreferring to FIGS. 2(a)-2(d).

In FIG. 2(a), the gas generant 3 in the form of pellets are charged intoa container body member 2a of the hermetic container and then thepartition foil piece 5 is placed on a surface formed by the chargedpellets 3 of the gas generant.

In FIG. 2(b), a press member 6 is placed on the partition foil piece 5to press it. The press member 6 comprises a disk like body 7 having aconcave curved surface facing to the partition foil piece 5 and adeformable pressure-transmitting member 8 which is mounted on theconcave curved surface and made of rubber or the like. Thepressure-transmitting member 8 transmits the pressure from the pressmember 6 to the partition foil piece 5 by its deformation.

When vibration is applied, the gas generant pellets 3 are chargeddensely by the vibration and by the action of the load of the pressmember 6.

Accordingly, the position of the surface formed by the charged pelletsmoves from a position indicated by a phantom line to a positionindicated by a solid line. At this time, the whole shape of the surfaceformed by the charged pellets 3 is made convex to conform to the profileof the concave curved surface of the press member 6. As shown in theenlarged view of portion A (see FIG. 2(e)), the deformablepressure-transmitting member 8 of the press member 6 presses thepartition foil piece 5 against the gas generant 3 by deforming subtly inaccordance with the uneven surface formed by charged pellets of the gasgenerant 3. Therefore, the partition foil piece 5 deforms according tothe profile of the surface formed by the charged pellets 3. Thedeformable pressure-transmitting member 8 can be made of a pile of manythin aluminum foils, sponge, and other materials, as well as rubber.

In FIG. 2(c), the press member 6 is removed. If the press member 6 wasremoved in the prior art wherein the partition foil piece 5 does notexist, the surface formed by the charged pellets of the gas generant 3lifts up during transportation for the next manufacturing step.Consequently, the densely charged state of the gas generant could not bemaintained. On the contrary, even if the press member was removed in thepresent invention, the partition foil piece 5 has still deformedaccording to the profile of the surface formed by the charged pellets ofthe gas generant 3 since it was deformed by the press member. Hence, thegas generant 3 does not move and the densely charged state of the gasgenerant can be maintained.

I n FIG. 2(d), the cushioning member 4 is placed on the partition foilpiece 5. The lid member 2b is put together with the top end of thecontainer body member 2a. The end portion (a) of the lid member 2b iscrimped and sealed to clamp edges of the container body member 2a, andthus fabricating the hermetic container for gas generant is completed.

The gas generant 3 does not interfere with crimping the en d portion (a)of the lid member 2b since the surface formed by the charged pellets ofthe gas generant 3 is convex.

A finished product can be obtained with maintaining the densely chargedstate of the as generant 3 according to the present invention. As aconsequence, the amoun t of the charged gas generant 3 can beincorporated.

Another gas generator according to the present invention is described byreferring to FIG. 3, wherein the gas generator has a combustion chamberin which gas generant pellets 3 are directly placed.

In this gas generator, the combustion chamber 18 is constructed of abody 11b, a cover 11a and a partition wall 17 having gas exit holes 15.Gas generated in the combustion chamber 18 passes through the gas exitholes 15 and a filter 14 following the route illustrated by arrow inFIG. 3, and flows out from the gas exit openings 16.

Sealing foils 13 are stuck to the gas exit holes 15 to maintain anairtightness of the combustion chamber 18. A strength of the sealingfoil 13 is that of the same foil as is destroyed by the pressure of theburning gas. For example, an aluminum sheet having a thickness rangeabout from 0.15 to 0.25 mm can be used. The sealing foils 13 may bestuck at any desired as long as the airtightness can be maintained. Forexample, the foils may be installed at the gas exit openings 16 of thegas generator. A numeral 12 shows a filter playing a role of a coolantalso.

The gas generant pellets 3 are directly charged into the aforementionedcombustion chamber 18. A cushioning member 4 is placed on the surfaceformed by the charged pellets of the gas generant 3 in order to suppressthe movement of the pellets 3 due to vibrations by a resilient force ofthe cushioning member 4. The cushioning member 4 is made of unwovenfabric consisting of ceramic fibers.

A partition foil piece 5 which is non-reactive with the gas generantpellets 3 is disposed between the cushioning member 4 and the surfaceformed by the charged pellets of the gas generant 3. The shape of thepartition foil piece 5 conforms to the profile of the surface formed bythe charged pellets. When the partition foil piece 5 is made of analuminum foil, the thickness of the foil is preferably set from 0.075 to0.15 mm. When the partition foil piece 5 is made of stainless steelbased on an iron alloy, the thickness of the foil is preferably set from0.02 to 0.04 mm.

One method of fabricating the novel gas generator having the combustionchamber 18 in which the gas generant pellets 3 are directly charged inaccordance with the present invention is next described.

The body of the gas generator is prepared, which has the sealing foilswhich are stuck to either the gas exit holes 15 as shown in FIG. 3 orthe gas exit openings 16 so as to maintain the airtightness.

The gas generant pellets 3 are directly charged into the combustionchamber 18 in the body 11b of the gas generator. Then, theaforementioned deformable partition foil piece 5 is placed on thesurface formed by the charged pellets of the gas generant 3. Thereafter,the pellets 3 are pressed through the partition foil piece 5. At thesame time, vibration is given to the pellets. As a result, the pellets 3are charged densely. The partition foil piece 5 is deformed according tothe profile of the surface formed by the charged pellets. Then, thecushioning member 4 is placed on the top surface of the partition foilpiece 5. Subsequently, the cover 11a closes the body 11b of the gasgenerator.

The pressing step is carried out by placing a press member on thepartition foil piece 5. The press member is similar to the press member6 shown in FIG. 2.

The closing step is carried out by a friction welding. The inner surfaceof the cover 11a may be rubbed against the cushioning member 4.

After this friction welding, the cushioning member 4 is pushed into thecombustion chamber 18 by about several millimeters. Alphabet (b) in FIG.3 shows the closed surface.

Another gas generator according to the present invention is nextdescribed by referring to FIG. 4, wherein a combustion chamber 18 of agas generator is directly loaded with gas generant pellets 3. In thisgas generator, a holding member 19 for a cushioning member 4 is mountedbetween a cover 11a and a partition foil piece 5.

When a size of a space for accommodating the cushioning member 4 can notbe established accurately because the gas generator is fabricated by thefriction welding, a gap may be created between the cushioning member 4and the cover 11a. In this case, it happens that the resilient force ofthe cushioning member 4 is not transmitted to the partition foil piece5.

Therefore, according to the present invention, the cushioning member 4has been previously fixed inside the combustion chamber 18 by theholding member 19 in a step of placing the cushioning member. Thecushioning member 4 can press the partition foil piece 5 with anappropriate pressing force. In FIG. 4, the holding member 19 is mountedin the combustion chamber 18 by means of pressure inserting. The cover11a closes the body 11b after the cushioning member 4 is fixed by theholding member 19.

In the description provided thus far, pellets are prevented from beingpowdered by vibration, which are accommodated in a certain space havingairtightness. However, it is not always required that the space haveairtightness.

Any kind of chemical gas generant can be used in this embodiment as longas the gas generant is pelletized. The most preferable gas generants arethose made from azide-based materials.

The present invention is adapted for a gas generator, a method offabricating the gas generator, and a method of fabricating a gasgenerant container for the gas generator, which enable the amount ofcharged gas generant to increase, which can prevent gas generant pelletsfrom being powdered by vibration for lapse of long time and which doesnot contaminate generated gas.

Obviously, numerous modifications and variations of the presentinvention are possible in light of the above teachings. It is thereforeto be understood that within the scope of the appended claims, theinvention may be practiced otherwise than as specifically describedherein.

What is claimed is:
 1. A gas generator for an air bag, comprising:acombustion chamber; a hermetic container accommodated in said combustionchamber; gas generant pellets charged in said hermetic container, saidhermetic container having a wall adapted to be destroyed duringcombustion of said gas generant pellets; a partition foil piece adaptedto cover a surface formed by said gas generant pellets charged in saidhermetic container so as to conform to a profile of the surface formedby said gas generant pellets, said partition foil piece beingnon-reactive with said gas generant pellets and having a strength lowerthan that of said hermetic container; and a cushioning member adapted topress said partition foil piece toward said gas generant pellets by aresilient force of said cushioning member so as to suppress movement ofsaid gas generant pellets charged in said hermetic container.
 2. A gasgenerator of claim 1, wherein said hermetic container includes acontainer body member and a lid member mounted on said container bodymember, said container body member containing said gas generant pellets,said lid member having said cushioning member therein.
 3. A gasgenerator of claim 2, wherein said hermetic container is made ofaluminum foil.
 4. A gas generator of claim 2, wherein said partitionfoil piece is made of aluminum.
 5. A gas generator of claim 1, whereinsaid hermetic container is made of aluminum foil.
 6. A gas generator ofclaim 5, wherein said hermetic container has a thickness of from 0.15 to0.25 mm.
 7. A gas generator of claim 1, wherein said partition foilpiece is made of aluminum.
 8. A gas generator of claim 7, wherein saidpartition foil piece has a thickness of from 0.075 to 0.15 mm.
 9. A gasgenerator of claim 1, wherein said partition foil piece is made from amaterial including iron alloy.
 10. A gas generator of claim 9, whereinsaid material is stainless steel.
 11. A gas generator of claim 10,wherein said partition foil piece has a thickness of from 0.02 to 0.04mm.
 12. A gas generator of claim 1, wherein said cushioning memberconsists of unwoven fabric made of ceramic fibers.
 13. A method offabricating a gas generant container for a gas generator of an air bag,comprising the steps of:charging gas generant pellets into a containerbody member of the gas generant container including thin walls adaptedto be destroyed during combustion of said gas generant pellets; placinga partition foil piece on a surface formed by said gas generant pelletscharged in said container body member, said partition foil piece beingnon-reactive with said gas generant pellets and having a strength lowerthan that of said container body member; pressing and vibrating said gasgenerant pellets charged in said container body member so as to denselycharge said gas generant pellets in said container body member, said gasgenerant pellets being pressed via said partition foil piece such thatsaid partition foil piece is deformed so as to substantially conform toa profile of the surface formed by said gas generant pellets charged insaid container body member; and fastening a lid member having acushioning member therein to said container body member so as to presssaid partition foil piece toward said gas generant pellets.
 14. A methodof claim 13, wherein said pressing and vibrating stepcomprises:utilizing a press member having a press surface facing to saidpartition foil piece, said press surface having a concave curved shapeand a deformable pressure transmitting member.
 15. A method offabricating a gas generator of an air bag, comprising the stepsof:charging gas generant pellets into a combustion chamber locatedinside a body of said gas generator including sealing foils adapted tobe destroyed by a pressure of burning gas during combustion of said gasgenerant pellets, said sealing foils being placed either at exit holesfor the burning gas discharged from said combustion chamber or at exitopenings for the burning gas discharged from the body of said gasgenerator; placing a partition foil piece on a surface formed by saidgas generant pellets charged in said combustion chamber, said partitionfoil piece being non-reactive with said gas generant pellets and beingdeformable so as to substantially conform to a profile of the surfaceformed by said gas generant pellets charged in said combustion chamber;pressing and vibrating said gas generant pellets charged in saidcombustion chamber so as to densely charge said gas generant pellets insaid combustion chamber, said gas generant pellets being pressed viasaid partition foil piece such that said partition foil piece isdeformed so as to substantially conform to the profile of the surfaceformed by said gas generant pellets; setting a cushioning member on saidpartition foil piece; and closing the body of the gas generator with acover.
 16. A method of claim 15, wherein said setting step comprises:fixing said cushioning member inside said combustion chamber by aholding member.
 17. A method of claim 15, wherein said closing stepcomprises:carrying out a friction welding.
 18. A method of claim 15,wherein said pressing and vibrating step comprises:utilizing a pressmember having a press surface facing to said partition foil piece, saidpress surface having a concave curved shape and a deformable pressuretransmitting member.
 19. A gas generator for an air bag, comprising:acombustion chamber; gas generant pellets charged in said combustionchamber; a partition foil piece adapted to cover a surface formed bysaid gas generant pellets charged in said combustion chamber so as toconform to a profile of the surface formed by said gas generant pellets,said partition foil piece being non-reactive with said gas generantpellets and having a strength sufficient to maintain its shapeconforming to the profile of the surface formed by said gas generantpellets after said partition foil piece is deformed so as to conform tothe profile of the surface formed by said gas generant pellets; and acushioning member adapted to press said partition foil piece toward saidgas generant pellets by a resilient force of said cushioning member soas to suppress movement of said gas generant pellets charged in saidcombustion chamber.
 20. A gas generator of claim 19, wherein saidpartition foil piece is made of aluminums.
 21. A gas generator of claim20, wherein said partition foil piece has a thickness of from 0.075 to0.15 mm.
 22. A gas generator of claim 19, wherein said partition foilpiece is made from a material including iron alloy.
 23. A gas generatorof claim 22, wherein said material is stainless steel.
 24. A gasgenerator of claim 23, wherein said partition foil piece has a thicknessof from 0.02 to 0.04 mm.